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23 September 2020, Blog #546

A 1971-built, Britten-Norman Islander was scheduled to operate a passenger flight from Antigua to Montserrat, 2 years ago on this date. One pilot and six passengers would be onboard the aircraft for the very short flight. (35 miles - 57 kilometres as the crow flies)

The aircraft in its final position after coming to a stop (© AAIB)


The pilot completed the required pre-flight checks without any abnormalities found, once the passengers were boarded the pilot gave a safety briefing to the passengers. This briefing included the use of seatbelts and emergency exits. After the engines were started the aircraft taxied to the runway, and once take-off clearance was received a normal take-off followed. Once airborne the aircraft climbed in VMC conditions to a height of 2000 feet. (VMC - Visual Meteorological Conditions). Due to the heavy rain showers on route and over the destination the aircraft flew to the north of the island of Montserrat and flew a holding pattern while maintaining visual contact with the sea, awaiting the heavy showers to clear.

The aircraft about to touchdown, picture taken from airport CCTV (© AAIB) After the showers had cleared there were some stratus clouds at 100 feet height, with the wind indicated as 140º at 6 knots. The flight was cleared to join a left-hand downwind for Runway 10 at Montserrat. The runway edge lights were on and the runway was wet after the showers. Th approach was flown with flaps full down and an approach speed of 65 knots at a height of 1000 feet. ATC provided surface wind information, 210º at 6 knots, resulting in a tailwind for the aircraft so ATC offered Runway 28. The pilot declined the offer and continued down the 6º glide path and touched down positively, however faster than normal.Montserrat John A Osborne Airport looking towards the north-east Brakes were applied after touchdown, momentarily released as they seem to be ineffective, and then reapplied. The brakes had little effect even when the brake pedals were depressed further. When the aircraft approached the end of the runway the pilot applied full right aileron and right rudder, so as to turn the aircraft onto the grass adjacent to the runway in an attempt to avoid going down the cliff at the end of the runway. The aircraft started to skid and turn 180º to the right before going backwards over the edge of the airfield, coming to a stop against the airport perimeter fence with its tail section. After coming to a stop the pilot selected the engine mixture levers, magnetos, fuel and electrical master switch all off. None of the occupants sustained any injuries and all evacuated the aircraft through the normal doors.

The damaged tail section of the aircraft (©AAIB) Damage to the aircraft was substantial;

  • The left stabiliser main spar was broken and bend upwards

  • Elevator damaged

  • Left wingtip damaged

  • Left aileron damaged

  • Blisters on the mainwheels

  • Left main landing gear displaced outwards

Montserrat John A Osborne Airport looking towards the north-east (© AAIB)

An investigation was launched by the Air Accident Investigation Branch (AAIB). In their report, published on the 21st of May, they came to the following conclusion;

"There were no faults or malfunctions of systems or equipment within the aircraft contributory to this accident. It appears that either increased airspeed over the normal approach speed of 65 kt was used or a significant change in windspeed and direction led to an increased tailwind component, causing a touchdown groundspeed of 79 kt. This, combined with a wet runway and skidding, greatly increased the LDR (Landing DIstance Required) beyond that available and led to the overrun."


Safety recommendations are made regarding aircraft operations at John A. Osborne Airport, access for rescue and firefighting vehicles, and a means of arresting aircraft that overrun the runway. The AAIB report, on which this blog is based, is available for reference by clicking on the .pdf file below, it contains detailed information from the investigation;

B N Islander Runway Overrun 23-sep-2020
.pdf
Download PDF • 6.41MB

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